Automatically-threading shuttle.



i E. s. STIMPSON.

AUTOMATICALLY THREADING SHUTTLE. APPLICATION FILED OUT. 12, 1908.

933,728. Patented Sept. 7, 1909.

sn'rns ATEN enrich.

EDWARD S. STIMPSON, I-IOPEDALE, MASSACHUSETTS, ASSLlGNOR T0 DRAFER COM- PANY, OE HOPEDALE, MASSACHUSETTS, A'CORPORATION OF MAINE.

AUTOMATICALLY-THREADING SHUTTLE. i

Specification of Letters Patent.

Patented Sept. '7, 1 909;

Application filed October 12, 1908. Serial No. 457,254.

'ment in Automatically l hreading Shuttles,

of which the following description, in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

This invention'relates to shuttles adapted for use in looms wherein the working shuttle is provided automatically with a fresh supply of filling from time to time while the loom continues to run. Such shuttles are provided with means to assume control of the incoming filling thread when a replenishment of filling is effected and to direct such thread automatically to the deliveryeye of the shuttle, from which eye the thread thereafter is drawn as the shuttle is thrown or picked back andforth through the shed.

Ordinarily, in the numerous types of automatically threading shuttles here-inhefore devised, the threading device on the shuttle assumes control of the new thread and directs it into a thread passage on the first shot of theshuttle following replenishment, and .on the return shot the thread is directed automatically into the delivery-eye. the threading being thereby completed. If the control of the thread is not assumed on the first shot the thread will be broken on the return shot, and in some structures if the initial control is not carried on to a certain point the thread is broken on the second 'shot, requiring another operation of the replenishing" mechanism.

.r'inother form of tin-aiding device has been devised wherein, if threading is not completed on the second shot after replenish1nent,tho thread may draw freely and uninterruptedly from a part of the threading device independently of the delivery-eye without affecting the proper operation of the loom, and the beak under which the thread passes is rearwardly curved and I turned away from the nearer tip of the shuttle. to facilitate the threading operation and also to shed an occasional loop which is some times formed and thrown forward onto the beak. Such a structure forms the subject matter of the United State Patent No. 769914 granted toNorthrop September l3. 1904, and my present invention is of the general S. STIMPsoN,"

type disclosed in that patent and is an improvement thereon. in certain features of construction to be pointed out hereinafter. My present invention also comprehends the construction of the threading device from sheet-metal, pressed or otherwise shapedup from blanks'in such manner that each and every threading device will be a counterpart of all the others turned out by the sa1neap paratus or mechanism.

At the present time the threading devices are almost universally made as castings, and while supposedly all of the threading devices of a given shape and structure are duplicates as a matter of fact there are sutlicient differences, due to shrinkage or warping of castings, or to other causes,' as to require careful testing and more or less tuningup and fitting of practically every casting of a lot before it will Work as designed in the shuttl'e. This imposes an additional cost on the manufacture, involving time and the em- )loyment of skilled labor, and reduces the output ,correspondingly.

In my present invention the threading de-. vice. is duplicated time after time by the forming mechanism, which is exact and positive in its operation so that the devices require no subsequent hand labor in fitting and correcting faults arising in the course of manufacture.

In order to adapt sheet metal to the desired use while obtaining certain features in the completed structure I have devised certain novel details of construction and arrangement which will. be described in detail. hereinafter the threading device being made in two parts and then assembled to form a unitary article.

Figure 1 is a'top plan View of the eye end of a shuttle containingmy present invention; Fig. 2 is a front elevation thereof: Fig. 3 is a front ele ation of the threading device removed from the shuttle, the separablemembers of said device being shown assembled and locked together; Fig. 4: is a similar view of the inner member of the threading device; Fig. iris a perspective view of said member; Fig. 6 is a perspective view of the other or outer member of the threading device; Figs. 7 and 8 are end elevations of the assembled threading device, looking at Fig. 3 from the right and left, respectively; Figs. 9 and 10 are plan views of the blanks from which the outer and inner members, re-

5 ectively, of the threading device are 'fgrmed. Fig. 11 is a top plan View of the metallic bushing or liner for the eye of the shuttle, and which alsoserves as a guide for the thread as its direction is changed to pass through the eye; Fig. 12 is a perspective View of the liner, viewed from its inner end.

The shuttle A has the usual bobbin-receiving opening'A common to shuttles of thistype, and an open delivery-eye a provided with an entrance slot 0., Fig. 2, the shutt le wood being suitably recessed to receive the threading device and having a directingchan'nel A inclining downwardly and away from the tip of the shuttle, the front wall a of the channel continuing to the entrance slot a, the'inclined or sloping bottom of the directing-channel being shown by dotted lines Fig. 2, the'eye having a metallic liner to be referred to hereinafter.-

As previously stated the threading device is made of sheet-metal, such for instance as steel, which can be readily died or stamped I and then in suitable forming presses or dies is given the required shape and contour for efiecting the functions required of the ,com-

pleted device.

The blanks B and C, Figs. 9 and 10, show the outline for the two parts or members'of the threading device, in accordance with my present invention, the blank'B being bent along the dotted lines 6", Fig. 9, to form upturned and parallel front and rear walls I),

b, Fig. 6, the bottom 6 being extendedat one end at b and notched at b, the extension serving as a locking device, as will be fdescribed. The blank is bent laterally in 'the same direction at the tops of the walls,

7 along the lines I Fig. 9, the substantially triangular head I) being thereby formed on the front wall, to lie upon the-shuttle body adjacent the entrance slot (1, the curved'forwardedge b of the head assisting in directing the thread into such slot-as it draws around and slides down the horn b formed by the inclined forward edge, of the wall I). At its lower end the horn is provided With a heel b, which as shown by dotted lines Fig. 2 is positioned with relation to the eye a in tlhe eye after it has been drawn under the bee The elongated, bentover portion 22 at. the top of wall I) and joining the head fits into aishallow recess in the top of the shuttle Wood and assists in positioning the thread- 1 ing device.

' So; far as described the head, horn and heeljare in their contour, arrangement and f] the patent hereinbefore referred to.

' blank 'B is sofshaped, however, as to provide function similar to corresponding parts in The for abeak b at'the upper end of the horn, said beak being bent and extended rearwardly ovcr the thread passage, to be re-- to cotiperate therewith'and retain the thread and its'forwar'd face is in aplane inclined with respect to the longitudinal axis of the shuttle and also with respect to the tip of the shuttle, so that the thread will slip easily over the beak and off its point during the threading operation,-and the beak will also shed a loop if thrown forward thereupon, as

in the patent referred to. The bent over portion of the blank at the top of the rear wall b forms a transversely wide and longitudinally prolonged shield b which is extended fron'tward and overlaps thev beak, as shown,

the front edge I) of the shield being convexed and crossing above the base of the beak, at quite a distance in front of the point If, as very clearly shown in Fig. l, the front edge b of the shield being con tinued forward toward the shuttle-tip well beyond the edge I) of the head. The shield is downcurved in the direction of its length over the beak, and at its forward extremity passes into a depression in the shuttle Wood,

the widest part of the shield being at the corner 6" formed by the intersection ofits edge 7) with its forward edge b, which latter is diagonal and also inclined downwardly from front to ream-passing down into the directing-channel A and intersecting the plane of the under edge of the beak substantially at the median line of the thread passage, said edge Z2 extending below the beak at its rear end, Figs. 7 and 8. I

From Fig. 2 it will be seen that the major portion of the forward edge 6 of the shield is below the front wall a of the channel A, for a purpose to be, described.

So far I have described but one member of the threading device, and for convenience in its operative position in the shuttle, and now I will describe the other member of said device and its several features of construction.

By bending theblank C along the lines 0* two-upturned, parallel walls 0, c are provided, which constitute a thread passage C through which the thread travels from the bobbin to the delivery-eye after the shuttle has been threaded a projecting part c at the top of the rear wall 0 being inclined frontwardly and downwardly to assist in directing the incoming thread tothe passage. The bottom 0 of the passage is prolonged at 0", and'at its forward end the front wall has a prolongation v0 the said wall having at its.

top at the other end. a rearwardly extended As shown in Fig. 4: the forward end of the wall 6 1s somewhat higher than the top of the prolongation 0", to pass under the shield when the two members are assembled and assist in positioning them.

' The two parts or members, shown sepa rately in Figs. 6 and 5 are assembled by sliding the member illustrated in Fig. 5 into the other member, the walls 0, 0 just fitting closely between the walls b, b, the tip of the prolongation abutting against the concave side of the beak at its base and operatively positioning the two members. At such time the bottom portions 0 0- are superposed, Fig. 3, and the extension projects beyond the ends of the upright walls,

shown. The locking portion 0 of the outer member is now upturned into final position, Fig. 3, and dotted lines Fig. 6,

against the extension 0, thereby locking the members of the threading device together and at the same time forming a seat for a friction-pad F of flannel, felt. or other suitable material. The notch Z)" allowsfor-thewearing down of the pad by the constant passage of the thread and obviates contact of the thread with the metal of the extension 11 The members, having been assembled as described, and in operative position .relatively, Figs. 3, 7 and 8, are now mserted 1n the shuttle, the thread passage C being alined with the directing-channel A and communicating therewith. A suitable retaining bolt D is extended transversely through the shuttle and passes through registering holes 6 and 0 in the upright walls of the members of the threading device, and' the shuttle is ready for use.

In order to 'line the shuttle-eye and obviate the employment of wear-resisting pins often used, and also to furnish a convenient and effective guide for the thread as it turns in its path from the thread passage through the eye I have provided a metallic bushing or liner, preferably of hardened steel, which is inserted in the eye a and fixedly secured in place.

The-liner is shown separately in Figs. ll and 12, and comprises a tubular body a cut away at its inner end at c at the forward side of a longitudinal entranceslot e in the top of the liner, the body having an external transverse notch 0 formed therein adjacent its inner end and intersecting the longer wall of the slot. The liner is driven into the eye a with'a drivingfit, the entra'nce'slot e being upper-most and registeringwith the slot a, to afford an inlet for the thread, and when in position the notch e of the liner is entered by the upright edge 6 of the front wall of the outer member of the threading device, as shownin Fig. 1, see the dotted lines, thereby preventing any longitudinal v movement of the liner. As the upright edge L fits squarely against the bottom of the notch e the liner is held from any rotative movement, and the heel I) of the horn dips downward above the cut away portion 6 of the liner, leaving an open unobstructed'path for the thread as it is drawn down the horn, under the beak and thence into the slots a, into the body of the liner. The inner end of the liner is rounded over-to form a smooth, curved face over which the thread draws, doing away with the use of a guide pin, as heretofore, and-similarly the outer end is rounded over. i

tothe threading operation, when the bobbin is inserted in the shuttle the filling thread leading therefrom is directed by the parts 0 and c down to the narrow inlet or entrance 0 and thence into the thread passage, the thread being drawn under the guard c and lying at first upon the top of the shield b, and the shuttle makes its first shot away from the replenishing side of the loom. As the shuttle moves away in a diagonal path, owing to the backward swing of the lay, the thread will generally be drawn across the convex front edge I) of the shield and onto the top of the head I), sliding rearwardly thereover onto the top of the beak and under the shield, the pull on the thread causing it to travel along over the apex b of the beak and off its point, and at the same time the thread is positively engaged and depressed by the forward edge 6 of the shield and thereby forced to .move downward and'rearward under such forward edge 5 into and along the channel A As the thread is thus drawn along it is shed from the'beak and immediately passes under it, extending through the thread passage C forward along the channel A After the shuttle completes its pick the filling thread laid is beaten in, the shed changes, and the shuttle is shot across on the return pick. The thread is now drawn out of the channel along the forward edge I) of the shield past the apex 71 and strikes the head D ata point on the edge 7) quite a distance in front of the bend or apex 5 of the beak,the thread then being guided between th edge I) and the wall a? down into. the slots a, c, the bight of the thread around the horn sliding down under the heel 5 into the eye, the (ZOlIlPlOtC threading of the shuttle having been thus effected. 'lhereafter, if the thread should be thrown out of the eye and slot toward the shuttle-tip it will meet thefront edge I) ofthe shield and be thrown back onto the headbflso far in front of the turn b r the beak that the bight of thread 'cain not be drawn around the beak to be shed therefrom and escape out. of the threading passa e, should the finger 0 fail to hold it.

Re erring to Fig. 1 it will be clear that the thread, after it has once passed under the beak, cannot approach the turn or ape thread may kink or curl.

- has been explained. Should a long loop be formed and thrown forward it would not ordinarily be caught on the beak, for the shield would act to throw the loop onto the head 6 toward the front of the shuttle at a distance from the a ex of the beak, but if the bight of the loop s iould be thrown under the shield and around the beak at its base the tightening of the thread will cause the beak to shed the loop without harm. I thus have provided such a thread controlling or threading device that the thread, when once under the beak on the firstpick or shot after replenishment, must enter the delivery-eye on the second or return pick and cannot be drawn over or shed from the beak; and this has not heretofore been possible to insure with fine and kinky filling while still retaining the loop shedding structure of the beak.

It is particularly to be observed that when the thread is drawn under the shield on the first shot after replenishment the diagonal and inclined forward edge I) of the shield acts to positively depress and at the same time force the thread rearward as it draws over-the wall 0 and as the edge 6 intersects and extends below the plane of the under edge of the beak the thread is thereby drawn down positively over and is shed off the upper edge of the beak. This positive control and movement ofthe thread downward and rearward to carry it beneath the beak is altogether different from the sliding movement of the thread rearward over the head and the top of the beak, which is practically the-action in shuttles of this general type as usually constructed. This con struction practically insures the positioning of the thread-under. the beak and in thethread passage'and directing-channel on the first shot of the shuttle after replenishment, and as stated when so positioned the thread on the return shot must of necessit be drawn frontward wet the edge b o the head and pass into the eye a. Howey'er, if

the thread by kinking o'r twisting, or from d any other cause, shou only passl'underthe' guard 0-on the first'shot', lying upon the shield or on the head .5 and not beneath the beak, the return shot will not cause breakage for the thread will then draw freely over the concaved forward edge of the guard, which then serves as a leader to deliver the thread properly independently of the eye of the shuttle. The finger on the guard, ex-

tended forward toward the beak, assists inretaining the thread inthe thread passage at the inner or entrance end thereof, as it approaches very closely the rear wall of the thread passage, so that after the thread has been drawn down under the guard it is practically impossible for it' to escape from the passage through the narrow inlet.

In referring to different parts of the shut tle and the threading device the front of the shuttle is regarded as that side or wall thereof nearest the front .of the loom, and

I claim as new and desire to secure by, Let- I ters Patent is 1. An automatically-threadingshuttle having an open delivery-eye, and a threading device provided with a thread passage, said device having a' horn terminating in a beak rearwardly extended over the thread passage and having a substantially horizontal lower edge, and a frontwardly-extended shield overlapping the beak and downcurved toward the shuttle-tip, the forward,diag0nal edge of the shield being downwardly mclined from front to rear of the-thread passage and crossing the. plane .of the under edge of the beak and continuing below the same, to first positively engage and depress the filling thread and thereby draw it over and then downward beneath the beak, and said edge thereafter acting to guide the thread frontward and-to a point beyond the apex of the beak, thereby preventing the thread from pulling upward oil" the beak and out of the thread passage.

2. An automaticallysthreading shuttle having an open delivery-eye and a threading device provided with a thread passage, said device having a horn terminating in an elongated, tapered beak extended rearward over the thread passage and turned away from the shuttle-tip, and a frontwardly' ex-' tended shield overlapping the beak and downcurved toward the shuttle-tip,2"the= shield being extended frontwardbeyond. the

apex. ofth'e beak and 'forwardof the same,

the diagonal forward edgefof the shield b'eing; downward- 1y inclinedxfrom frontto rear :of the thread passage and'crossing the plane of the under edgeof the beak substantially seams at the median line of the passage and terminating below the beak, said forward and in clined edge acting to engage and positively depress the thread and carry it downward beneath the beak.

An automatically-threading shuttle hav ing an open delivery-eye and a threading device provided with a thread passage, said device having a beak rearu 'ardly extended across the thread passage and having a substantially horizontal under edge, and. a

frontwardly extended shield overlapping the beak and downcurved' toward the tip of the shuttle, the forward diagonal edge of the shield being downwardly inclined from the front to the rear of the thread passage, and extending below the plane of the under edge of the beak, and beyond the tip thereof to ward the rear of the passage, and the front edge of the shield projecting frontward beyond the apex of the beak, to prevent engagement of the thread with the beak behind or at its apex and consequent escape over the beak and out of the passage.

t. An automaticallythreading shuttle havan open delivery-eye and a threading device provided with a thread passage, and an inclined horn to direct the filling thread from the passage to the delivery-eye, the horn having a heel at its lower end and at its upper end a head terminating in a beak directed away from the shuttle-tip and extended rearwardly over the thread passage, and a downcurved, frontwardly extended shield at the rear side of said passage to overlap the beak, the shield having its front 1 named i'nember overhanging the inner end of edge longitudinally convex and crossing the beak at a distance from and in front of its apex, the forward edge-of the shield being inclined and diagonal from front to rear of the shuttle to positively engage and depress the thread and carry it under the beak, the.

thread. after passing under the beak being,

directed by the forward and frout'edges ol the shield onto the head at a point at the base of the beak in front of its apex, to prevent. the thread from 'i'iassiug behind the apex and thence oil' the beak.

An autoi'natieally-threading shuttle havin an open delivery-eye and a two-part sheet-metal threading devi ie, one member thereof having upturned walls the front one terminating in. a horn having a rearwardly turned beak and. the rear one having a frontwa rdly extended shield overlapping the beak, the other member having upturned. walls forming a thread passage and slidable into operative position between the walls of the first-named member, a lock on the latter to hold the members together, and a fixed guard on the front wall of the second-named men'iber overhangmg the thread passage, to 1st in directing the till1ng-thread into and a; prevent its escape from the thread passage and serving also as a guide for delivery of thread independently of thedeliveryhold the members together, the front wall of the second-named member having a pro long-ation to abut against the base of the beak and form a positioning stop for the two members, and a guard on said front wall overhanging the thread passage at its inner end.

7. An automatically-threading shuttle havingan open delivery-eye and a two-part sheet-metal threading device, one member thereof having upturned walls the front oil'e terminating in a horn having a rearwardly turned beak and the rear one having a frontwardly extended shield overlapping the beak, the other member having upturned walls forming a thread passage and slidable' into operative position between the walls of the first-named member, a prolongation at the inner end of the first-named member adapted to be upturned against the inner end of the bottom of the thread passage, to form a lock holdin the two members to ether and b n b a fixed guard. on the Iront wall of the secondthread-directmg guard on the inner front wall overhanging the thread passage, a horn on the outer front wall having a beak turned rearwardly over the passage at its outer end, a frontwardly extended shield on the outer rear wall overlapping the' beak, and a locking projection on the outer member of the threading device, upturned at the inner end of the thread passage and forming therea-t. a pocket for a friction pad. S). An aut n'iatically-threading shuttle having an open delivery-eye and a threading device composed of two members made of sheet metal and slid into position one within the other, the inner member having a thread passage and a fixed guard. overhanging its inner end, means on the outer member to cooperate with the inner member and lock it in operative position, a horn on the outer member terminating in a beak, and a shield on said member overlapping the beak, the shield being downcurved over the beak and having its forward edge below the under edge of the beak.

10. An automaticallythreading shuttle having a side delivery-eye anda two-part sheet-metal threading device to direct the filling thread to the eye, one member having upturned parallel walls the front one terminating in a horn having a beak and the rear wall having a shield frontwardly extended and downcurved to overlap the beak,

the second member having upturned parallel walls, the front wall having a prolongation to abut against the base of the beak and form a positioning stop, the forward end of the rear wall rising beneath the shield, the walls of the second-named member forming a thread passage and sliding into position between the walls of the first-named member, and a tongue on one member to engage '25 the other member and lock them together.

11. An automatically-threading shuttle having a delivery-eye and a directing-channel inclining downwardly from the tip of the shuttle, and a-threading device provided with a thread passage in substantial alinement with said channel, the threading device having'a born with a heel at its lower end and at its upper end provided with a beak extended rearwardly over the thread )assage, and a frontwardly, extended shleld overlapping the beak and down curved toward the shuttle-tip, the forward, diagonal edge of the shield being downwardly inclined from front to rear to positively en- 40 gage and depress the thread below the beak and having its major portion. below the front wall of the directing-channel and continued below the plane of the under edge of the beak and beyond it to the rear of the thread passage.

12. An automatically threading shuttle having an open delivery-eye and a threading device composed of two members-"made of sheet metal and slid into position one within )0 the other, the inner member having a thread passage and a fixed guard overhanging its inner end, means on the outer member to co operate .with the inner member and lock it in operative position, a looprshedding beak on-the outer member, and a shield on said member overlapping the beak and having itsfront edge extended toward the front of the shuttle at a distance beyond the apex of the beak, the shield being longitudinally curved over the beak and having its forward ed e inclined downward and rearward belowt e beak. i

V 13. An automatically threading shuttle having a side delivery-eye. and an entrance slot therefor, a metallic liner inserteddn the eye and having a longitudinal slot register ing with said entrance slot, a threading olevice to assume control automatically of the filling thread and direct it into the eye, and means on the threading device to interlock with and retain the liner in position by the threading device.

end above the cut-away part of the liner, 80. I

the thread passing down the born under the heel and passing into the liner by means of the slotted entrance and the cut away portion, the liner thereafter serving as aguide for the thread as it passes out of the shuttle. 15. An automaticallythreading shuttle having a side delivery-eye and an entranceslot therefor, a metallic liner inserted in the eye and having a longitudinal sl'ot registering with said entrance slot, said liner having an external notch at its inner end, and a threading device to assume control of and automatically direct the thread into the liner, said device engaging the notch in and preventing rotative or longitudinal more ment of the liner in the delivery-eye.

16. An autoi'natically-threading shuttle having a transverse eye and an entrance slot leading thereto, a metallic thread-gnide and lining for said eye, inserted therein and hav' ing a slot registering with the lower end of' the entrance slot, said guide and lining having a transverse notch, and a threading device to assume control of and direct the thread to the eye and having a part enter? ing the notch, to retain the lining in the eye and also holding it against rotation. I

17. An automatically-threading shuttle having an open delivery-eye and a two-part sheet-metal threading'device provided with a horn having a" rearwardly turned beak, and a frontwardly extended shield overlapping the beak, each member having up-' turned opposite walls, the walls of one member fitting into operative position between the walls of the other member and forming a thread passage, means to hold said members in cooperative relation, and a fixed guard on the front wall of one of said mem bers overhanging the thread passage, to assist in directing the filling-thread into and preventing its escape from the thread passage and serving also as a guide for delivery of the thread independently of the deliverye w. v

'18. In an automaticallythreading shuttle, a deliv cry-eye, a rearwardly turned beak having its point turned away from the nearer tip' of the shuttle, and a shield overlapping the beak and acting to depress the a thread below the same, and extended frontdistance in front of and also'extend'ed for ward beyond the a ex of the beak, such edge livery-eye.

ward to present a front edge substantially parallel to the front wall of the shuttle and beyond the apex of the beak, to guide the thread toward the delivery-eye, the front edge actin to 'revent the thread, after it has passe un er the beak, from beingdrawn backward over the beak behind the apex.

19. An automatically-threading shuttle having a delivery-eye and a threading device including a rearwardly extended loop-.

shedding beak, a hornbelow the-beak, a shield overhanging the latter and acting to depress the thread below the beak and having its front edge crossing said beak'at a holding the threa toward the front of the shuttle after the thread has passed underthe beak and preventing engagement of the .thread with the forward edge of said beak near or to the rear of its apex, and a 'heel on thehorn to prevent withdrawal of the thread after it has been drawn into the de- 20. An automatically-threading shuttle having an open delivery-eye and a'two-part sheet-metalthreading device, each member havin upturned,-opposite and longitudinally extended walls, the wallsof one member fit ting into operative'-. .position between the walls of the other member and forming a thread pasage, one of the front walls terminating in a horn having a rearwardly turned beak, and a front-wardly extended shield 'on a rear wall, overlapping the beak,

means to lock the two members in coo erative relation, and a fixed guard on the; rent wall of one of the members overhanging the inner end of the thread passage and .co-f

operating with the, rear wall of the thread passage to provide a narrow inlet therefor.

21. A thread controlling and directing de-. vice for automatically-threading shuttles,

made .of sheet-metal and comprising opposite. walls to form a thread passage, a beak,

and a shield having a forward diagonai edge, the beak extending across and having its point turned away from the outer end and overlapping the beak, the front edge of the shield crossing the beak ,at a distance from and in front of the apex thereof, the forward diagonal edge of 'the shield bein of the thread passage, the shield extending, in the opposite direction over the passagedownwardly inclined from abovevthe bea: at one side ofthe thread passage toward the opposite side thereof beyond the point of and extending below the under edge of the beak, said diagonal edge acting, in the threading operation, to positivel engage and depress 'the thread below the eak, and the-front edge of the shield at such time preventing engagement of the thread with the beak at it's a 'ex or between the apex andiv presence of 

